Nauru government spokesperson Joanna Olsen told ABC local radio that a quater of the hospital was burned down in the fire overnight.
"The medical store and the pharmacy was destroyed, so I'm not sure if the hospital has supplies elsewhere at a different site," Ms Olsen said.
"I haven't been able to confirm that yet but those two buildings that I know of that hold all the medical supplies are gone."
Medical records, and X-ray facilities have alo been destroyed, but wards and patients have not been affected.
Locals have been tweeting that two fire trucks were onsite at the hospital to bring the fire under control while volunteers helped to evacuate the patients.
2 fire trucks onsite at #Nauru hospital. Fire is now under control. Hundreds of people onsite. Many volunteered to evacuation all patients. — Clint. Deidenang (@clintd22) August 14, 2013
No injuries have been reported, so far.
